There has been a catastrophic fire at a chemicals factory near Basel, Switzerland, sending tons of toxic chemicals into the nearby river Rhine and turning it red.

The fire broke out early this morning in a storage building used for pesticides, mercury and other highly poisonous agricultural chemicals.

Local residents were woken by sirens sounded by local authorities to alert them to the disaster.

People in the city of Basel and the surrounding region on the border between Germany and France were told to stay indoors.

Witnesses reported a foul smell of rotten eggs and burning rubber.

Fourteen people, including one of the firemen fighting the blaze, were treated in hospital after inhaling the fumes.

Crucial waterway

It is thought the chemicals were washed into the river in the water used by firefighters to tackle the fire. The West German Chemicals Industry Association is to carry out an internal report and says it could take weeks to determine the cause of the disaster.

The factory is owned by Sandoz, one of Switzerland's largest chemical firms.

About 30 tons of pesticides were discharged into the river, western Europe's most important waterway.

The river flows through four countries - Switzerland, Germany, France and Holland - before flowing into the North Sea.

Environmentalists are now struggling to prevent the pollution sweeping down the Rhine and into the rest of Europe.

The spillage has reversed 10 years of painstaking work to clean up the Rhine, so grossly polluted by industrial expansion in France, Germany and Switzerland that fish disappeared and it was too dangerous to swim in.

The Dutch are particularly concerned about the presence of mercury in the chemical cocktail now heading their way.

A similar pollution incident in Japan 25 years ago revealed the extremely poisonous nature of mercury after fish were contaminated and then caught and eaten by fishermen and their families in the area.

Hundreds of people suffered an agonising death as a result of that incident, which saw mercury deposits similar to those expected to accumulate along the North Sea coast near Holland.